Strapping machine



July 7, 1964 M. B. HALL ETAL 3,139,813

STRAPPING MACHINE Filed Oct. 2, 1961 9 Sheets-Sheet 1 6 6 J1 k-lllllll 141 1569i llllllll II II I July 7, 1964 M. B. HALL ETAL STRAPPING MACHINE 9 She ets-Sheet 2 Filed Oct. 2, 1961 July 7, 1964 M. B. HALL ETAL 9,8 3

STRAPPING MACHINE Filed Oct. 2, 1961 9 Sheets-Sheet 5 July 7, 1964 M. B. HALL ETAL 3,139,813

STRAPPING MACHINE Filed Oct. 2. 1961 9 Sheets-Sheet 4 July 7, 1964 M. B. HALL ETAL 3, 39,813

STRAPPING MACHINE Filed Oct. 2,1961 9 Sheets-Sheet 5 July 7, 1964 Filed Oct. 2. 1961 M. B. HALL ETAL STRAPPING MACHINE 9 Sheets-Sheet 6 July 7, 1964 HALL ETAL 3,139,813

STRAPPING MACHINE Filed Oct. 2. 1961 9 Sheets-Sheet 7 July 7, 1964 Filed Oct. 2, 1961 M. B. HALL ETAL STRAPPING MACHINE 9 Sheets-Sheet 8 July 7, 1964 M. B. HALL ETAL STRAPPING MACHINE Filed Oct. 2, 1961 9 Sheets-Sheet 9 TENSION 8: GRIP MRHURL STRRP FEED SEAL. FEED STRAP FEED United States Patent 3,139,813 STRAPPING MACHINE Marchand B. Hall, Olympia Fields, Willard E. Collins, Clarendon Hills, Robert F. Plattner, Chicago Heights, and Edward D. Finnegan, Jr., and Frank C. Weller, Chicago, IlL, assignors to Acme Steel Company, Chicago, 111., a corporation of Illinois Filed Oct. 2, 1961, Ser. No. 142,351 16 Claims. (Cl. 100-4) This invention relates to the art of strapping machines and particularly to an improved strapping machine for binding by encircling an object, package, box or other bundle, with a loop of strap having its supply and leading strap ends overlapping each other and joined together by means of a joint formed by interlocking the strap ends with an encircling tubular metal seal.

A study of the strapping machine art shows that many strapping machines for encircling and securing a binder strap around an object are extremely complicated and expensive to manufacture and seem to perform with varying degrees of efliciency. Based upon some of the strapping machines designed and sold on the market it appears that low selling price has not been the major objective in their design and it is known that many of the strapping machines available have been in very expensive price ranges of thousands of dollars.

With the onslaught of competition, there has been a greater desire by those in the strapping industry to produce a compact strapping machine at a very low cost which is capable of performing as well and better than available expensive machines. With this in mind, the applicants have for their principal object the provision of such a compact strapping machine which is efficient and versatile in its operation and which can be manufactured at relatively low cost.

In keeping with this major objective, it is another object of the invention to provide a strapping machine provided with a single air operated motor for strap feed, strap slack take-up and strap tensioning. Heretofore, it was not uncommon to provide separate means for each or combinations of these functions. It has been found that an air motor has advantages because it can be reversed in a simple manner by merely reversing the direction of air feed to it and it can be easily controlled for strap tension by varying the air line pressure, the desired strap tension being reached when the air motor stalls. On other machines, for example, elaborate means have been used for these operations, including auxiliary shafts in addition to the main shaft and magnetic clutches for reversing rotation, separate motors have been used, one for feeding and another for take-up and tensioning, and somewhat elaborate mechanism has been employed for strap tension control. Where electric motors are used in strap tension devices they are cumbersome because they are much heavier than air motors and stalling of an electric motor for control of strap tension presents heating and electric overload problems which usually require more complicated mechanisms to overcome. The use of an air motor eliminates the elaborate means and effects a substantial cost saving.

In line with compactness, it is another object of the invention to provide an improved signalling means which provides a signal to the sealing means when strap tensioning is completed in order to sequence the sealing and other operations required after strap tensioning is completed. The technique employed in this invention is relatively simple because it relies upon displacement of at least a portion of the strap feed means due to deflection and/or penetration into the strap being fed by teeth provided in a strap feed and tensioning wheel due to forces of tension as tension in the strap increases to pro- 3,139,813 Patented July 7., 1964 vide the required signal initiating the subsequent functions of the machine.

it is another object of the invention to provide time delay means associated with the signalling means related to tensioning which insures that full strap tension is reached before sealing can occur. This is especially important when the object being strapped is compressible and when more than one strapping machine is being used to simultaneously apply a multiple number of straps to the package. It has been found that full tension may be instantaneously reached in a compressible package before the package has been fully compressed. If sealing occurs during this instant of temporary full tension, the package can later compress further so that the strap tension is objectionably relieved. The device of this invention insures that full compression of the package is achieved so that full tension is reached and maintained with no subsequent slackening of tension. In addition, when strapping a plurality of straps simultaneously on a compressible package by means of a plurality of strapping machines, this invention insures that all of the straps will have achieved their full tension before any of the sealer mechanisms of the plurality of strapping machines used will operate. If one strap loop would be allowed to be sealed before full tensioning on all of the straps is completed, the straps ordinarily would end up with unequal strap tensions and this is very objectionable.

Another object of the invention is to provide an improved strapping machine without the conventional type seal support portion ordinarily used to support a seal preliminary to joint formation, and still permit the use of a common type inverted channel-shaped seal.

It is still another object of the invention to provide improved strap support means in the. joint forming region during the joint forming period. The improved strap support means consists of a guide and gripping jaws which support overlapping portions of the strap at one end of the sealing region and strap gathering jaws which support the strap portions at the other end of the sealing region. The strap portions bridged between the gripping jaws and guide on one end of the joint forming region and the strap gathering jaws at its other end are thereby supported together for proper joint formation.

It is still another object of this invention to provide such sequencing of the machine that the seal is fed into sealing position only after the strap is initially fed past the functional parts of the machine in order to allow clear passage of the strap without the possibility of its end snagging on the seal or the seal feed bar. It is this feature of the machine which permits the elimination of special support means for the seal as mentioned because the strap is positioned for guiding of the seal and for its support prior to the time it is fed into position.

Another object of the invention is to provide positive sequencing between the seal feed device and the gathering or strap support jaws to insure that a seal is positioned in sealing position before the gathering jaws are positioned where they would block passage if a seal would be attempted to be fed after they are positioned.

In conforming to the minimizing of the number of parts and employing special sequencing mechanism, the leading strap end gripping or holding jaws and the tensioning motor are actuated simultaneously by havin their pneumatic operating means in parallel with each other. In other strapping machines, there is employed a positive sequencing so that the leading strap or holding jaws are positively gripped before strap tensioning occurs This requires special sequencing means and adds to the cost. Applicants have realized that sequencing for this purpose is not essential and have eliminated it.

It is another object to provide a strapping machine having a sequence where strap feed follows joint formation and allows for seal feed before joint forming, retraction of the seal feed mechanism during joint forming, and retraction of the joint forming or sealing means in addition to the retraction of the seal feed mechanism prior to strap feed. The seal feed means must be retracted to clear the sealing or joint forming region of interference from the seal feed means, and both the seal feed means and the joint forming means must be clear of the strap path before strap feed for the particular machine embodiment disclosed.

It is still another object of the invention to provide a strapping machine where the strap gathering jaws which grip beneath the strap at one end of the sealing or joint forming region are of a type which not only support the strap, but also have improved design which incorporates a strap end stop for limiting how far the strap can be manually inserted into the sealing region after it has been encircled around an object to be strapped. On some other strapping machines where this operation is manual, no stop is provided for the strap end and, so, the strap end becomes positioned varying distances beyond the joint forming region to result in a waste of strap in the form of a free strap end protruding beyond the sealed joint after strapping is completed.

It is another object to provide improved leading strap end gripping means embodying toothed or serrated gripping jaws which grip the leading strap end against a blade having grooves formed therein in matching position to the teeth on the jaws in order to insure proper gripping during tensioning of the strap.

It is still another object to provide such a machine With, a deflecting plunger means for deflecting the leading strap end away slightly from the face of the strapping machine in the region leading to the seal storage region so that the strap is prevented from snagging on the seal storage and seal feeding mechanisms or a seal ready for being fed.

Another object is to provide improved means for eliminating bends or deformations of the strap end induced by bending around corners of the objects strapped. It is common to withdraw a strap portion which has been so bent back into the region of joint forming during strap slack take-up and tensioning. If the bend is not removed, the strap will not subsequently feed properly so that great difficulty arises. This is an aggravated source of trouble which is at least substantially eliminated by the improved means of this invention.

Other objects and advantages of the invention should become apparent upon reference to the accompanying drawings, in which FIG. 1 shows a perspective view of a portion of a roller support type conveyor line provided with a strapping machine embodying the invention;

FIG. 2 shows a side elevation of the strapping machine shown embodied in the apparatus of FIG. 1;

FIG. 3 shows a rear elevation of the machine shown in FIG. 2;

FIG. 4 is a side elevation of the middle portion of the machine as viewed in FIG. 2, except that it is shown enlarged and oriented through ninety degrees;

FIG. 5 is a partial front elevation of the machine as viewed from the right in FIG. 2;

FIG. 6 shows a bottom end view of the machine;

FIG. 7 shows a top end view of the machine;

FIG. 8 shows a partially cutaway and sectional view of the machine as viewed in the same direction as shown in FIG. 2;

FIG. 9 shows a perspective view of a box or package provided with a binder strap as it would appear after being applied with the apparatus of this invention;

FIG. 9a shows a perspective view of a typical channelshaped seal employed with the apparatus of this invention;

FIG. 10 shows a perspective view of a typical sealed joint applied by the apparatus of this invention to the overlapping strap ends of a strap loop encircled about a package;

FIG. 11 is a sectional view as viewed along the line 11-11 of FIG. 4 and particularly shows the leading strap end gripping mechanism;

FIG. 12 is a sectional View along the line 12-12 of FIG. 4 and particularly shows the strap shearing mechanism, the strap joint sealing mechanism and the latching mechanism for controlling the actuation of strap gathering jaws;

FIG. 13 shows a sectional view along the line 1313 of FIG. 4 of the strap straightening mechanism;

FIG. 14 is a sectional view along the line 14-14 of FIG. 2 and illustrates the supporting shaft for the strap feed idler wheel;

FIG. 15 shows the lower left hand portion of FIG. 7 on an enlarged scale;

FIG. 16 is a sectional view along the line 16-16 of FIG. 4 and particularly shows the mechanism for actuating the strap gathering jaws;

FIG. 17 shows a simplified schematic of the electrical circuit used for control of the operating portions of the machine, and

FIG. 18 shows a diagrammatic representation of the pneumatic circuit used to power the operations of the machine.

As shown in FIG. 1, the strapping machine or head 1 embodying the invention is shown positioned between two roller conveyor lengths 2 and 3. The head 1 is shrouded with a cover 4 for better appearance and to protect the operator from accidental injury because of otherwise exposed moving parts. The roller conveyor lengths 2 and 3 are suitably supported with leg supports 5, 6 and 7, as required, and the strapping head 1 is suitably supported on a pipe frame 8. In front of the head and extending below the upper level of the conveyor lengths 2 and 3 is a channel-shaped strap guide 9 for suitably guiding a loop of strap 10 around a package 11 being strapped and insuring that the leading end of the strap loop is properly fed under the package 11 and up into proper location with the working parts of the strapping head 1. It should be observed that the front strapping region 1a of the strapping head extends vertically in the particular arrangement shown, but the head can be oriented to any angle so that the front strapping region 1a can extend in any direction, including facing either upward, downward or sideways at any angle. The arrangement shown in FIG. 1 is intended for purposes of example only.

Without the shroud cover 4, the strapping head 1 is especially shown overall in FIGS. 2, 3, 5, 6 and 7. It is provided with a single large rectangular plate 12 which is the main support frame for all of the components of the strapping head. The major operating portions of the head consist of the strap feed, slack take-up and tensioning portion 13, the leading strap end gripping portion 14, the strap shear portion 15, the joint sealing or forming portion 16, the strap gathering jaw portion 17, and the strap seal storing and feeding portion 18. In addition, there is a valve manifold 19 which houses three air valves for controlling the air powered portions of the machine powering the portions 13 to 18.

The strap feed, slack take-up and tensioning portion 13 is provided with a serrated rotary feed wheel 20 which is secured to the end of a shaft 21. The shaft 21 is the drive shaft of an air motor 22 provided with a flange 23 which is secured to the main frame 12 by means of screws 24-. The air motor 22 is mounted on one side of the frame 12 and projects through a circular hole 25 to the other side of the frame 12. The rotary feed wheel 20 is positioned so that the teeth or serrations 26 about its periphery are parallel to an annular wall 27 on a strap feed idler wheel 28 adjacent to it. The idler wheel 28 is considerably larger in diameter than the rotary feed wheel and it is mounted, as particularly shown in FIGS. 2, 3, 6, 8 and 14 on a bearing 30 to the outer end of a shaft 29. As an idler, it is free to rotate on the bearing 38 relative to the shaft 29. The shaft 29, in turn, is

secured at its inner end to a nange 31 which is secured to one end of a larger shaft 32. The shaft 29 is mounted on the flange 31 with its center eccentric with the center of t e shaft 32. The shaft 32 is mounted between bearings 33 and 34 in a bearing housing 35 secured to the frame 11.2 by means of bolts 36. The other end of the shaft 32 is secured to the lower end of an arm 37 which extends radially outward from the shaft 32. The intermediate portion of the arm 37 is provided with an opening through which freely passes a threaded shaft 38. The threaded shaft 33 is on a stud 39 which is secured to the frame 12. The other end of the threaded shaft 38 is provided with a threaded nut 33b which retains the arm 37 from falling off of the shaft 33. Between the arm 37 and a portion near its end 38a where there is a threaded nut 38c is a coil spring 4t reacting between the nut 33c and the arm 37 to apply a rotating force on the shaft 32 tending to urge it in a counterclockwise direction shown by the arrow 41 in FIG. 2.

The free end of the arm 37 is secured by a universal coupling 42 to one end 43 of a rod 44. The other end 45 of the rod 44 is in line with the actuating arm 46 of a switch LS3. The rod 44 is used to cause actuation of the switch LS3 upon rotational movement of the shaft 32, as will hereinafter be described.

Around the lower portion of the idler wheel 28 is a guide 47 which is used to guide strap around the idler wheel in the region from adjacent to the rotary feed wheel to the front surface of the head.

Above the level of the strap feed, slack take-up and tensioning portion 13 is a strap straightening region 48 (FIGS. 2, 4, 8 and 13). This region is provided with a block 49 hollowed out to contain a strainghtening roller 5th. The straightening roller 50 is mounted on a shaft 51 which has a threaded end 52 eccentric from the main body portion of it where the roller 50 is mounted. The shaft 51 is held securely on the block by means of a threaded nut 53 secured on the threaded shaft end 52. This shaft 51 is eccentric of the threaded end 52 so that it can be adjustably rotated to adjust the position of the roller 50 toward or away from a curved region 54 of a blade 55. The strap is adapted to pass between the roller 5'59 and the portion 54 of the blade 55 where it is deformed through a curved path for purposes of straightening the strap. The eccentric adjustment is ordinarily intended when changing from one strap thickness to another.

Above the level of the straigtening region 48 is the leading strap end gripping portion 14. It is particularly shown in FIGS. 2, 4, 5, 8 and ll. and consists of two grippers 56 and 57 which are pivoted on two pins 58 and. 55% mounted between two side plates 60 and all. The grippers 56 and 57 are provided with sharpened jaws 555a and 57a which are adapted to react against the leading end of the strap when it is positioned beneath the blade 55. The blade 55, as shown in FIG. 5, is provided with transverse grooves 55a which align with the sharpened jaws 56a and 57a so that the strap, when gripped, is deformed slightly into the grooves 55:; for tight gripping. Each of the sharpened jaws 56a and 57a have as many sharpened edges on them as there are grooves 555; in the blade 55.

The blade 55 is secured by means of screws 62 to an arm 63 joined to the frame 12 by means of a screw 64. This blade 55 has the multiple functions of assisting in strap straightening and strap gripping, as described, and also its leading edge 55% acts as a shear blade, as hereinafter described. It has an additionl function of strap guiding because its rear end (FIG. 8) extends substantially to the region of the guide 47 where it guides the strap from the idler wheel 23 all the way into the joint sealing or forming portion 16.

The upper ends of the grippers 56 and 57 are pivoted on pins 65 to two toggle links 66 which are pivoted on a pin 67 to a yoke 68. The yoke is secured to the piston rod 69 of a piston contained in the air cylinder 79. In

operation, the grippers 56 and 57 are positioned as shown in FIG. 11 and the piston rod 69 of the air cylinder 79 is retracted at that time. Upon extending of the piston rod 69 by admission of air in the proper direction to the air cylinder 76, the pin 67 is moved to cause the link 66 to pivot the grippers 56 and 57 and cause their jaws 56a and 57a to grip a strap positioned beneath the blade 55. The cylinder 76 is secured by screws '71 to a pair of supports 72 which are provided with a cover plate 73 and secured by means of screws '74 to side plate 6t). Above the blade 55 in this region is a fixed strap guide 75 which has a groove 75 formed in it to provide an opening larger than the thickness of strap to be used where the supply strap end can be guided and moved freely even'though the leading strap end is gripped in a fixed position against the lower surface of the blade 55 during tensioning.

Forward of the leading strap end gripping portion 14 is first the strap shear portion 15 and then the joint sealing or joint forming portion 16. Both of these are shown especially in FIGS. 2, 4, 5, 8 and 12 and are contained between the two parallel side plates 66 and 61. Both of the side plates 60 and 61 are held apart and in parallel relationship by means of four spacers 77, 78, 79 and hit. The side plates are assembled to the spacers by means of bolts 77a, 78a, 79a and 3th: so; as to provide a substantially closed boxed in structure. A sheet metal cover plate 81 surrounds a portion of the structure in order to conceal its mechanism. This housing is hooked around the spacer at one end and hooked onto the spacer 77 at its other end. It is easily removable for servicing the mechanism.

The mechanism for joint scaling in the region 16 consists of a plurality of six jaws 32 and 83. There are, in this particular showing, four jaws 83 positioned two each opposite the two others and two jaws 82 positioned one opposite each other. The arrangement is such that the jaws 82 are alternately sandwiched between the jaws $3. In addition, there are two fixed die members 84 on either side of the jaws 82. The jaws $2 and 83 are pivoted on pins 85 to the side plates 6t and 61 while the die members 84 are mounted in a fixed position on these pins 85. Each of thejaws 82 and 83 are provided with recessed portions 86 which are adapted to engage the edges of a seal and wrap it around overlapping strap ends adjacent to it and cause a seal joint to be formed by deforming the seal and strap ends with these recessed portions 86 as the seal reacts against lower surfaces 87 of the die members 84. The result is a seal joint 83 as shown in FIG. 10. This seal joint 88 has tabs 89 which are the regions contacted by the surfaces 87 and the die members 84 While the recessed portions 86 of the/sealer jaws engage beneath the remaining edge portions 91 It should be emphasized at this point that the particular sealer jaws and sealer mechanism generally used and shown herein are an example of a conventional type well-known in the art and it is not intended to be restricted to this particular form. It is shown merely by way of example.

In addition to the sealer jaws 32 and 83 being pivoted on the pins 85, they are also secured together by pins 91 so that they pivot integrally. The upper ends of the sealer jaws 33 are pivoted on pins 92 to two toggle links 93 and 94. These toggle links 93 and 94 are in turn pivoted together on a pin 95 which is mounted between two slides 95 and 5 7 (see FIGS. 4 and 12). The slide 96 is herein after referred to as the cross-head. Both the slide 97 and the cross-head 96 are provided with another pin 9% which is pivoted to two links 99, one adjacent to the slide 97 and the other adjacent to the cross-head 96. These links $9 are in turn pivoted on a pin 1% to a gear sector 101. This gear sector 161 is pivoted on a pin 102 between side plates 60 and 61. The gear sector has teeth 1d?) which normally engage teeth 104 on a rack which is guided in two oppositely positioned grooves 106 formed in the side plates 6% and 61. The rack N5 is mounted by means of two screws 1137 to the piston rod 1118 of the air cylinder 109 (FIGS. 2, 3, and 6) which is hereinafter referred to as the sealer cylinder. in operation, the sealer parts are initially retracted to their position as shown in FIG. 12. As the piston rod 108 is extended by admitting air under pressure in the proper direction to the sealer cylinder 109, the rack causes the gear sector 101 to rotate on its pin 102 in a clockwise direction, as viewed in FIG. 12, and this causes the sealer jaws to pivot in such a manner that the oppositely positioned recess portions. 86 are moved toward each other to cause the formation of a sealed joint when a seal encircling two overlapped strap. ends are present in the sealing region. After joint formation, the rack is returned by retraction of the piston rod 108 to return all parts of the sealer mechanism to their original positions as shown in FIG. 12. There is a shear blade 111) provided with elongated openings 111 through them and the shear blade is mounted by these elongated openings 111 on the stationary pins 85. Shear blade is also provided with shoulders 112 which ordinarily rest on pins 91. During actuation of the sealer mechanism, there are rollers 113 mounted on the pins 92 and these rollers engage the upper edge 114- of the shear blade as the sealer jaws 83 are pivoted. The result is that, with the proportion and positioning of the parts as shown, the shear blade 110 is moved downwardly by the rollers 113 during the last portion of the sealing stroke. This causes the lower edge 115 of the shear blade to shear through a strap positioned in its path by reacting with the end 55b of the blade 55. As the sealer partsare again retracted to their initial positions, the pins 91 engaging the'shoulders 112 of the shear blade cause it to also retract to its original position as shown in FIG. 12. Also pivoted on a pin 116 to the gear sector 101 is an Lshaped link 1117 having its other end pivoted on a pin 118 to a first latch plate 119. The latch plate 119 is mounted to pivot on a hollow shaft 120 (see FIGS. 4, 5, 12 and 16) which is secured to the side plate 61 by means of a nut 121 threadably engaging its threaded outside surface. The end of the shaft 12% which is visible in FIG. 12 is a flanged end while its remaining portion is that which is threaded. The flanged end retains the latch plate 119 on the shaft'120. Between the first latch plate 119 and the side plate 61 is a second latch plate 122 which is also pivoted on the shaft 121). It has a protruding portion provided with a pin 123 which projects into an opening 124 extending through the side plate 61. The pin 11% on the first latch plate 119 also protrudes through an opening 125 extending through the side plate 61. Both of the openings 124 and 125 are elongated to allow for a limited length of travel of the pins 118 and 123 during pivotal movement of both latch plates 11 and 122 on the shaft 120. A coil spring 126 surrounds the shaft 120 and has its opposite ends-connected around the pins 118 and .123 in such a manner that the latch plates tend to be rotated in opposite directions by the force of the spring 126. There is also a latch'bolt 127 of circular rod crosssection which protrudes through the hollow of the shaft 120. It is provided with a hook end 127a used ordinarily 'to engage one or both of two notches 119a and 122a provided on the latch plates 119 and 122 respectively. The other end 12% of the latch bolt 127 protrudes beyond the opposite side of the side plate 61 and it is provided with an encircling compression spring 128 which is mounted .to react against the first cotter pin 129 to urge the latch bolt to the right, as viewed in FIG. 4. This tendency of the spring 128 in this direction urges the end 127a of the latch bolt into the path of the notches 119a and 122a.

The pin 123 is also engaged with a slot 130 in a triangular shaped link 131. This link 131 provides a toggle with another link 132 to which it is pivoted by a seal storing and feeding portion 18. shown in FIGS. 2, 3, 4, 5, 7, 8 and 15 where a seal storage turn is pivoted on a pin 137 secured to the side plate 61. The link 132 is also pivoted on a pin 138 to the upper end of another gathering jaw 139 on a pin 141i mounted in the side plate. 61. This mechanism embodying the gathering jaws 136 and 139, as viewed in FIG. 16, constitutes the strap gathering jaw portion 17.

In operation, the parts related to the gathering jaws are retracted by having the pin 133 toward the upper end.

of the slot 134 so that the lower end of the gathering jaws are spread apart from each other. This means that the pin 123 is held toward the bottom of the slotted opening 124 asviewed in FIGS. 12 and 16 with the latch plate 122 rotated to a position where its notch 122a is in alignment with the notch 11%v on the latch plate 119 and the end 127a of the latch bolt 127 is engaged with both notches. When it is time in the operating cycle of the machine for the strap gathering jaws 136 and 139 to pivot into their operative positions, the latch bolt127 is moved to the left, as viewed in FIG. 4. This allows the force of the spring 126 to pivot the link 1131 to its position as shown in FIG. 16 and this, through the toggle arrangement of links 131 and 132, causes the proper pivotal movement of the gathering jaws so that their free ends are brought toward each other to intersect the ordinary path of the binder. strap during the operation of the machine. Next, after the strap gathering jaws are positionedas shown in FIG. 16, the gear sector 191 is rotated by the rack 1115 in order to move the link 117 to the right as viewed in FIG. 12. This causes the latch plate 119 to rotate clockwise and have its notch 119a moved to a position where it is coincident with the notch 122a. When it reaches thisposition, the end 127a of the latch belt 127 again engages the notch 122a and this occurs at the end of the joint sealing operation after strap shearing has occurred. Next, the rack 1115 is retracted to rotate the gear sector 1111 in the opposite direction and pull the link 1117 to the left as viewed in FIG. 12 to rotate both of the latch plates 119 and 1122 together until pin 118 returns to the left end of the slot 125 and the pin 123 returns to the lower end of the slot 124,'as viewed in FIG. 12. The movement of the latch plate 122 at this time causes the toggle linkage associated with the gathering jaws 136 and 139 to spread their. free ends apart from each other and out of the ordinary path of travel of strap. With all parts returned, they are ready for a repeat cycle of operation.

. Beyond the strap gathering jaw portion 17 is the strap It is particularly magazine 141 extends along the outside wall of a side plate 61a. Side wall 61a is immediately adjacent to side wall 61 and it is secured to it by means of the same bolts 77a, 78a, 72a and 811a which maintain the side plates 69 and 61 assembled together with their spacers. Also, this side plate 61a is provided with an irregular cutout surface 6112 which provides room for the operating mechanism of the gathering jaws, as clearly shown in FIG. 16. In addition, a cover plate 610 is positioned over side plate 61a and this conceals the gathering jaw mechanism shown in FIG. 16. The bolts holding side plates 6311, 61 and 61a together also hold this side plate 610 assembled.

The seal magazine 141 houses a plurality of nested channel shaped seals 142 which have a shape as shown in FIG. 9a. Each seal 142 is provided with a back surface 142:: bridged between two depending legs 1421) which extend divergently away from each other. The seals 142 are stacked in the seal magazine 141 and retained in their stack by means of a spring loaded weight 143 and this manner of stackingand retaining the seals in a seal magazine is a relatively common expedient for a strapping machine. As shown in F168, the forward seal in the stack is positioned with its depending legs 1 12b resting on two plates 144 secured to the base of the seal magazine 141 by means of screws 145 (see FIGS. 4, 5 and 8). Pivoted on a pin 1% to the wall of the seal magazine 141 is a seal feed hinge 147. Its free end is provided 9 with a seal feed bar 148 pivoted to it on a 149 and this seal feed bar 1 .3 is urged in a clockwise direction (FIG. 8) by means of a spring 1511 coiled around the pin Another spring 151 encircles the pin 146 and reacts between the seal magazine 1 .1 and another pin 152 mounted through the seal feed hinge 147 in order to urge the seal feed hinge 147 in a clockwise manner. The free end 153 of the seal feed bar 1453 is notched with a little shoulder to engage the edge of the endrnost seal 142 when it is positioned with its depending legs 1 32b resting on the plates 144. Ordinarily, the seal feed hinge 147 is retracted to the position as shown in FIG. 8 with the seal feed bar 148 engaging the forward seal, but the forward seal is resisted from being displaced until the seal feed hinge 147 is pivoted on its pin 146 to drive the seal feed bar 148. As soon as seal feed hinge 147 is released, the endmost seal 142 is moved by the force of the spring 151 applied to the seal feed hinge 147 to cause the seal to be fed into a region between the sealing jaws 82 and 83 in preparation for sealing.

After a seal is fed, the pin 152 projecting laterally from the seal feed hinge 147 engages the extreme free end 1271) of the latch bolt 127 to immediately cause the positioning of the strap gathering jaws 136 and 139, as previously described. The seal feed hinge 147 is returned to its retracted position (1 16. 4) by means of a roller 154 moving against a surface 155 on a projecting portion of the seal feed hinge 147. The roller 154 (FIGS. 4, 7, l and 16) is mounted on a pin 1% to a yoke 157 at the end of an arm 158 which is part of the cross-head 9d actuated during movement of the sealing mechanism, as previously described. In order to clarify the relative sequential movement of the seal feed hinge 147 with the sealer mechanism, the seal feed hinge 147 is first moved from the position shown in FIG. 8 to feed a seal and it moves to a position shown in FIGS. 2 and 4 during this time. Then, the sealer mechanism is operated to form a seal joint 88 and move the roller 154 against the surface 155 of the seal feed hinge in order to again retract it during the joint forming period. There is a laterally extending plunger 159 (FIGS. 2, 7 and S) which is retracted through the frame 12 in order to release the seal feed hinge 147 initially. Upon return movement of the seal feed hinge to its position as shown in FIG. 8, an end surface 1&9 of a projecting ear 161 on the hinge 147 latches against the plunger 159 to retain the hinge in its retracted position.

Beyond the seal magazine 141 is a strap guide 152 which extends for some distance and is held in place by being bent around two pins 163 and 164 which are mounted in a guide support block 165. On both sides of the strap support guide 165 are mounted side guides 166 which are spring loaded against the guide support 165 and which can be spread apart to allow for removal of the strap from between them. Likewise, there are two side plates 157 and 168 mounted on opposite sides of the straightening portion 43, as shown in FIGS. 2, 4, 5 and 13. These are likewise spring loaded laterally against their support. Specifically, all'of the side guides 166, 167 and 158 are provided with inwardly turned flanges 166a, 157a and 168a for temporary strap retention. Also, the means for spring loading the guides toward each other is by means of identical springs 169 as best shown in FIG. 5. The spring consists of a helical coil body 169a secured at one end to a straight rod portion 169!) which passes centrally through the body portion 169a and terminates in a hooked end 16%. By passing the hooked end 16% through holes in each pair of oppositely positioned side guides with the hooked end 169a engaging a hole in the side guide positioned opposite to the side on which the body portion 169a is located, the proper retention of the side guides is achieved,

As shown in FIGS. 2, 4 and 8, the seal feed hinge 147 is provided with a V-shaped link 171) having a central flat portion 170b, It is connected at its one end to the hinge 147 by means of a pin 171. At its other end it encircles ill the pin 156 of the cross-head 96 so that its one end moves with the hinge 147 while its other end moves with the cross-head 9d. The reason for this is to prevent actuation of the switch arm 172 of the switch LS2 by means of the portion of the link 170 until both the seal feed hinge 147 and the sealer mechanism have been retracted. This is important to the control of certain operations of the machine as controlled by switch LS2. The essence of the importance of this arrangement is that the seal feed hinge 147 must be retracted before the sealer mechanism is retracted, but both must be retracted before switch LS2 is operated and strap feed is initiated.

As shown in FIGS. 5, 8 and 16, there is a spring loaded plunger 178 which is urged to the right as viewed in FIG. 8. The purpose of this spring loaded plunger is to deflect the leading end 173a of the strap when it is initially fed past the gathering jaw region 17 to deflect the strap end away from the seals stacked in a seal reservoir 141 to prevent contact of the strap end with the seal and thereby arrest strap feed. The tendency for this to happen would be increased in case of a strap with an end curved or otherwise deformed in a direction toward the seal magazine 141.

Before describing the electrical and pneumatic circuits, the following summary of the mechanical operation of the strapping apparatus is presented. Initially, the strapping head 1 is presented with a package 11 along its front face 1a. A length of strap 173 is fed from a suitable supply source through a guide 174 in the direction of the arrow 175 (FIG. 2) in order to feed the strap 173 between the rotary feed wheel 20 and the idler wheel 28. Then, the rotary feed wheel 20 is rotated by its air motor 22 to feed a length of strap around the idler wheel 28, through the straightening portion 48, past the leading strapping end gripping portion 14, the strap shear portion 15, the joint sealing or forming portion 16, the strap gathering jaw portion 17, the strap seal storing and feeding portion 18, and into a region beyond the side guides 166. This leaves a free end of strap protruding above the level of the strapping head 1 as it appears in FIG. 1. At this time, the seal feed hinge 147 is released by retracting the plunger 159 to feed a seal 142 into a position between the sealer jaws 82 and 83. The strap length positioned in the strapping machine acts as a guide along which the seal 142 is fed and it also acts as a retaining means to prevent the seal from dropping out of the head after it is fed. This leading strap end 173:: is grasped by the operator and manually encircled forward, around and beneath the package 11 and guided by the bottom of the guide channel 9 provided in front of the machine. This guide channel guides the strap up below the blade 55 between the side guides 167 and 168 of the strap straight ening portion 43, past all of the mechanism leading to the strap gathering jaw portion 17 and is finally deflected up onto a ledge 176 on each gathering jaw 136 and 141? where the leading strap end is arrested in its forward movement. The front of each gathering jaw is provided with a sloped surface 177 which provides the deflection for the strap end up onto the ledge 176. At this time, the package 11 rests on the conveyor lengths 2 and 3 with the strap loop 119 loosely surrounding it. The leading strap end gripping jaws 56 and 57 are then pivoted to grip the leading strap end 173a against the bottom surface of the blade 55 7 Next, the rotary feed wheel 20 is rotated in a reverse direction to cause reverse movement of the strap 173 in order to withdraw the slack from the strap loop 16 loosely surrounding the package 11. At the end of the strap slack take-up period, the rotary feed wheel 20 causes the strap 173 to be tensioned tightly onto the package 11. After tensioning is completed, a signal from the tensioning means causes actuation of thepiston of the sealer cylinder 1119 to cause the sealing portion 16 to form a sealed joint of the type shown in FIG. 10 between the overlapping strap ends of the strap. At the end of the joint forming stroke, the supply strap end is severed from the strap loop and the leading strap end gripping portion 14 is actuated in a direction to allow removal of the strap loop with the package 11 as the package 11 is moved downthe roller conveyors supporting it. Actually, the leading strap end gripping portion 14 is not released until the feeding of strap is initiated immediately after strap shearing. After a new length of strap has been fed into the machine far enough to pass between the guide plates 166 and beyond them, the machine is ready for a new operating cycle.

Having referred to the general operation of the machine, the electrical and pneumatic operations can be described with reference to FIGS. 17 and 18. In FIG. 17, which shows the electrical circuit, there are two electric wires 179 and180 which are connected to opposite sides of an electrical input. The wire 179 is connected to one side of a master switch 181 which has its other side leading through a wire 191 to a cycle switch 182 and a holding switch 183b in parallel with it. Both are connected through a switch LS1 to a junction 191 which carries four parallel branches leading to the wire 180 on the opposite side of the electricalsystem. The first parallel branch contains switch LS3, switch contact 184c,and the solenoid 190a of the sealer valve 190, .all in series. The second parallel branch contains relay switch 1841b and solenoid 184a of relay 184 in series with each other. The third parallel branch contains the solenoid 183a of relay 183. The fourth parallel branch contains solenoid 189a of the tension and grip valve 189. Also leading from wire 191 is a branchcircuit containing relay switch 18% and seal feed plunger solenoid 188. Also connected from wire 191 is .a manual strap feed switch 187 leading to a juncture 192 in parallel with switch LS2 leading to the same juncture 192. Beyond the juncture 192 are two parallel circuits, the first of which contains solenoid 1,855: of a time delay relay 185 and the second of which contains solenoid 186a of the strap feed valve 186. It should be mentioned that the relayswitches 184!) and 184a are actuated by energization and de-energization ofsolenoid 184a, relay switch 183b is actuated by relay solenoid 183a and relay switch 185i: is operated by relay solenoid 185a. Also connected from wire 179 to a point between relay switch 184a and the sealer solenoid 190a is a manual seal switch 203. A'wire 204 is also connected between a juncture 205 and 206 in two of the parallel branch circuits.

In FIG. 18, which shows the pneumatic circuit, there areshown the three control valves 190, 186 and 189 (these valve are physically positioned together in the manifold 19 as shown in FIGS. 2 and 3). A sourceof high pressure 193 is connected by a conduit 194 to the valve 190. The valve 190 is connected to the sealer cylinder 109 by means of conduit 200. The valve 190 is also connected to an exhaust conduit 195 andanother conduit 196. Both conduits 195 and 196 lead into valve 186 and this valve has two conduits 197 and 198 leading from it to the third valve 189. From valve 189 is an exhaust conduit 199 leading to the atmosphere. Both of the conduits 19.5 and 197 are connected to a common exhaust leading to exhaust conduit 199. Both conduits 196 and 198 are connected to the common high pressure conduit 194 leading from the high pressure source 193.

Leading from the valve186 is a conduit 201 which leads to one side of theair motor 22 and to one side of the strap end gripping cylinder 70. A conduit 202 leads from the valve 189 to the opposite side of their air motor 22 and to the opposite side of the strap end gripping cylinder 70. There is only a single conduit 200 leading to the sealing cylinder 109 because its piston rod 105 is of a spring return type. t

, To summarize the entire operation of the machine, with respect to the electrical and pneumatic circuits, initiallythe machine is put into operation by inserting the leading strap end 173a of a supply of strap between the rotary feed wheel 20 and the idler wheel 28. The supply ing circuits for their later operation.

12 of strap is ordinarily a coil of strap positioned in a convenient fixed place relative to the installation where the strapping head 1 is located. As shown in FIG. 2, the strap can be inserted through a guide 174 which leads into the region between the rotary feed Wheel 20 and the idler wheel 28. Also, the operator must fill the seal magazine 141 with a plurality of stacked seals 142 by first removing the spring loaded weight 143 and then replacing it after the seals have been placed in the mag azine. Initially, the seal feed hinge 147 is latched to a position indicated in FIG. 8, the manual seal switch 203 is open, the master switch 181 is open, the manual strap feed switch 187 is open and the cycle switch 182 is open. At this time, the master switch 182 is closed. This energizes the strap feed solenoid 186a and the time delay relay solenoid 185a through the contacts of closed switch LS2. Energizing the strap feed solenoid 186a actuates the solenoid valve 186 to cause air pressure from the high pressure source 193 to be fed through conduits 194 and 196 to conduit 201. The air pressure in conduit 201 feeds to both the air motor 22 and the leading strap end gripping cylinder 70. This maintains the piston rod 69 of the leading strap end gripping cylinder retracted so that the strap gripping members 56 and 57 are retracted out of the path of the strap. Feeding of the airpressure to the air motor 22 causes it to rotate the rotary feed wheel 20 in a direction to feed strap into the machine past the operating portions at the front face of the machine. The energized time delay relay solenoid 185a permits the strap to be fed for approximately one second for the particular embodiment shown. This is accomplished by having the solenoid delay the closing of its relay switch 185k for one second. After one second, the relay switch 18512 closes to energize the seal feed plunger solenoid 188. This causes the plunger 159 to retract and allow the seal feed hinge 147 to pivot from a position as shown in FIG. 8 to a position as shown in FIG. 2. During this time a seal is fed from the seal stack in the seal magazine 141 over the strap previously fed into the machine until the seal is positioned within the sealing region of the sealer jaws 82 and 83. The seal is arrested in its forward movement as it contacts the side plate 60. The pivoting of the seal feed hinge 147 immediately causes the arm 171 of switch LS2 to move and cause switch LS2 to open. This immediately de-energizes the solenoid 185a of the time delay relay and also the solenoid 186a of the strap feed valve solenoid 186a to arrest strap feed. As the time delay relay solenoid 185a is .de energized, its relay switch 1851) again opens to free the plunger 159 of the magnetic pull of the seal feed plunger solenoid 188. The plunger 159 is spring loaded .outward ly toward the flange 161 on the seal feed hinge 147 against which it rests at this time.

As the plunger 159 is retracted initially, it strikes the arm of switch LS1 to close it. Closing this switch LS1 merely prepares the strap tensioning, gripping and seal- Also, as the seal feed hinge 147 pivots downwardly, the pin 152 on it strikes the latch bolt 127 to release the latch plate 122 (FIGS. 12 and 16) and cause the gathering jaws 136 and 139 to assume positions as shown in FIG. 16 where their free ends are in the path of the strap.

The one second delay period for strap feed is calculated to feed out only enough strap that it projects slightly above the head as viewed in FIG. 1. This is not intended to be enough length of strap for encircling a package. Therefore, the manual strap feed switch 187 is closed to feed out additional strap by energizing the strap feed valve solenoid 186a. The manual strap feed switch 187 is held closed for as long a period as required to feed out the length of strap'needed. Even though the electrical circuit permits the time delay relay solenoid 185a to again be energized at this time, if it is energized long enough to allow its relay switch 1851) to close and energize the seal feed plunger solenoid 188, there is no greases physical effect at this time because the plunger is being held retracted by the flange 161 on the seal feed hinge 1417.

With sufiicient strap drawn off, the operator manipulates it over, around and beneath the package 11 to be strapped and forces the leading strap end 173a into the guide 9 below the top levels of the roller conveyors 2 and 3 where it is guided up into the working regions at the front of the strapping head 1. The strap is guided up through the strap straightening portion 48, and up onto the ledges of the strap gathering jaws 136 and 139.

It should be emphasized that the feeding of a seal is deliberately delayed until after the strap is fed into the machine during the one second time delay. The reason for this is to feed the strap into position with a minimum of possibility of the leading strap end 173a catching on anything in its path. With both the seal feed bar 148 and the seal to be fed out of the way at this time, there is a substantially clear path for the strap to follow without too much risk of snagging. The machine was deliberately designed with this sequencing of having the seal feed follow the strap feed to provide another advantage which is that the strap itself acts as a guide during the time the seal is fed into the sealer portion and the strap also acts as a support for the seal to prevent the seal from falling out of the machine. On prior devices, where the strap is not used to support the seal, separate holding means is required for the seal during strap feed.

Next, the cycle switch 182 is closed and this energizes the relay solenoid 183a and the solenoid 18% of the tension and grip solenoid valve 189. Energizing the relay solenoid 183a closes its relay switch 13% which acts as a holding contact upon release of the cycle switch 182 to its open position. When the tension and grip valve 189 is actuated at this time, it causes high pressure air to pass through the conduit 202 and into the opposite side of both the air motor 22 and the leading strap end gripping cylinder 70. Immediately, the piston rod 69 extends to cause the gripping jaws 56 and 57 to grip the leading strap end against the under surface of the blade 55 (FIG.

11). Simultaneously therewith, the air motor 22 rotates in a direction opposite to its rotation during strap feed and this causes withdrawal of the strap 1733 around the idler wheel 28 in a clockwise direction as viewed in FIG. 8. Strap withdrawal continues until all the slack is taken up in the strap loop encircling the package 11 and continues until a certain degree of tension is reached. When this certain degree of tension is reached, there is a certain deflection of the idler wheel shaft 29 and its elated parts and the shaft 21 of the rotary feed wheel 20 in combination with a certain movement resulting from penetration of the serrations on the rotary feed wheel into the strap. This movement of the strap feed parts by deflection and penetration provides a certain angular movement of the arm 37 and this in turn causes movement of the rod 44 to allow actuation of the switch LS3. Actuation of the switch LS3 at this time closes its contacts to energize the relay solenoid 184a of time delay relay 184. Energizing this relay solenoid closes relay switches 84b and 1840 after a short time delay. Closed relay switch 134!) is a holding contact for relay solenoid 184a. Closing of relay switch 184C causes energization of the solenoid 195M of the sealer valve 1%. This causes high pressure to flow through conduit 200 and into the sealer cylinder 169 to cause its piston rod 1% to extend and actuate the sealer jaws 82 and $3 to form a sealed joint 88 of the type shown in FIG. and thereafter sever the supply strap end from the strap loop 16 encircled about the package 11. The time delay provided by relay 1% insures that full tension is reached in the strap before the sealer mechanism is operated and provides enough time to insure that full compression of a compressible object being strapped occurs. Also, when a plurality of heads 1 are being used, the time delay is set long enough to guarantee that full tension is reached by all heads before any one operates to seal or form a oint.

, switches 184b and 134d During the shearing and sealing operation (FIG. 4) the roller 154 on the cross-head 96 (FlG. 16) causes the seal feed hinge 148 to again retract from the position as shown in FIG. 4 to its position as shown in FIG. 8 where the seal feed bar 148 has its end 153 engaging the edge of the next seal in the stack of seals held in the seal magazine 141. As the edge 160 of the flange lei on the seal feed hinge 14? passes by the seal feed plunger 159, the spring loading on the plunger causes it to extend and latch the seal feed hinge 147 against its end surface 16%. There the seal feed hinge 147 is held until seal feed plunger 159 is again retracted during the next cycle of operation.

As soon as shearing has occurred, during the final portion of the sealer mechanism stroke, the tension in the strap at the supply end is relieved. This relieves the deflection in the strap feed members 26 and 2% and their related parts in order to allow the arm 37 to pivot back to its original position. As this occurs, the rod 44 causes switch LS3 to again open. At this time, the seal feed hinge 147 is fully retracted to allow the plunger 159 to extend and open switch LS1. Opening switch LS1 deenergizes relay solenoid 183 and the solenoid 189a of the tension and grip 'valve 189. Opening switch LS1 also de-energizes relay solenoid 184a to again open its relay This causes de-energization of the solenoid 190a of the sealer valve 1% to relieve pressure from the air sealer cylinder 109 to the atmosphere through conduit 195. When this happens, the spring loaded return of the sealer cylinder 1639 causes the sealer parts to assume their original positions as shown in FIG. 12. During this return movement of the sealer parts, the cross-head 96 is retracted so that the V-shaped arm 17th is also fully retracted to where the portion 17% of this arm again causes movement of the switch arm 172 of switch LS2 to again close it. Closing of this switch LS2 initiates the one second time period of strap feed caused by the time delay relay and leaves the end of the operating cycle with a portion of strap fed into the machine and extending above the level of the strapping head 1. It is then in readiness for the next cycle of operation which is initiated by again closing the manual strap feed switch 187 to feed out a suificient length of strap to encircle the next object or package to be strapped.

There is an important feature of the machine which occurs at the time that the shearing of the strap occurs As soon as tne shearing occurs, there is an instant before high pressure is eliminated in conduit 2%. When this occurs, the supply strap end retracts through the region between the straightening roll 5% and the portion of the blade immediately opposite the straightening roll 50. This means that the leading strap end is passed reversely through this straightening device. When this occurs, this causes any kink or bend in the strap end to be removed so that upon subsequent strap feed in the forward direction, snagging is eliminated which might otherwise occur if the strap is bent. One of the principal reasons for a bend in the strap end results from the strap having been bent sharply around a corner of the package being strapped. if such a bend is not removed, it is a serious source of trouble. This straightening-device 48 eliminates this problem.

Ordinarily, at the time when the air is released from the conduit 2%, the leading strap end gripping piston rod 69 is urged to a retracted position by means of an internal spring. However, because of the gripping action between the gripping jaws on the strap loop on the package 21, the weight of the package is transmitted through the gripping jaws to Wedge them against the side plate fill of the head near which they are mounted. The spring return force on the piston rod 69 is not enough to overcome the wedging force to retract them. It is not until strap feed is subsequently initiated that the gripping jaws retract and their retraction is brought about by the admission of high pressure air into conduit 261 simulta neously with the admission of high pressure air from the conduit 2M to the air motor 22 for strap feeding. Note that the strapped package cannot be removed from the machine before this occurs because the gripping jaws are holding the strap loop up against the front face of the strapping head 1.

Although only a single embodiment of the invention has been shown and described, it should be understood that the invention can be made in many different ways without departing from the true scope of the invention as defined by the appended claims.

We claim:

1. The combination in a strapping machine comprising, gripping means for gripping the leading end of a length of strap encircled into a strap loop about an object to .be strapped with the leading end of the strap overlapping its supply end, tensioning means for withdrawing thesupply end of the strap loop relative to the leading end of the strap loop while the gripping means holds the leading end stationary in order to shrink and tension the strap loop onto the object, joint forming means for forming a joint between the overlapping portions of the strap, said tensioning means having a rotary feed wheeland an idler wheel between which the strap passes while being tensioned, said rotary feed wheel sup- --p.or.ted on a shaft driven by a power means for tensioning, said idler wheel being mounted on an eccentric shaft which is so aligned relative to the rotary feed wheel that tension in the strap urges rotation of the eccentric shaft and thereby urges the idler wheel bodily toward the rotary. feed wheel to increase the grip on the strap passed therebetween as strap tension increases, control means for controlling the operation of said joint forming means, saidv control means having a portion interconnectedto said eccentric shaft providing movement of said portion in response to said rotation of the eccentric shaft .as tension in the strap increases, the movement of said portion being suflicient to operate the control means and cause operation of the joint forming means.

2. The combination defined by claim 1 characterized by said control means being provided with a time delay which delays the immediate operation of the joint formingmeans.

3. The combination in a strapping machine comprising, gripping means for gripping the leading end of a .length of strap encircled into a strap loop about an object being strapped with the leading end or" the strap overlapping its supply end, tensioning means for withdrawing the supply end of the strap loop relative to the leading end of the strap loop while the gripping means holds the leading strap end stationary in order to shrink and tension the strap loop onto the object, joint forming means for forming a joint between the overlapping portions of the strap, said tensioning means having a rotary feed wheel and an idler Wheel between which the strap passes and is gripped while being tensioned, said rotary feed wheel supported on a shaft driven by power means for causing tensioning of the strap, said idler Wheel being mounted for rotation on an axis on a portion of an eccentric shaft journalled for rotation on a fixed axis, the axis of said portion being eccentric of said fixed axis on which the eccentric shaft is journalled and in a position which causes the idler wheel to be urged increasingly toward the rotary feed wheel by the t3 by, said control means provided with a time delay means which delays the immediate operation of the joint forming means.

5. The combination ina strapping machine comprising, gripping means for gripping the leading end of a length of strap encircled into a strap loop about an object being strapped with the leading strap end overlapping the supply strap end, tensioning means for withdrawing the supply strap end relative to the leading strap end while the gripping means holds the leading strap end stationary in order to shrink and tension the strap loop onto the object, joint forming means for forming a joint between the overlapping strap ends, said tensioning means having a rotary feed wheel and an idler wheel between which the strap passes and is gripped while being tensioned, said rotary feed wheel being supported on a. shaft driven by power means for causing tensioning of the strap, said idler wheel being mounted for rotation on an axis on a portion of an eccentric shaft journalled. for rotation on a fixed axis, the axis of said portion being eccentric of said fixed axis on which the eccentric shaft is journalled and in a position which causes the idler wheel to be vurged increasingly toward the rotary feed wheel by the increased force of tension developed in the strap during tensioning to increase the grip on the strap, said eccentric shaft'being provided with an arm positioned to move through an angular path as the eccentric shaft is rotated on its axis .to thereby cause said arm to actuate a switch means in response to bodily movement of the idler wheel toward the rotary feed wheel as the strap tension increasesv and cause actuation of the joint. forming means.

6. The combination defined by claim 5 characterized by, said switch means including a time delay means which "delays the immediate operation of the joint forming means.

7. The combination in a strapping machine comprising, joint forming means in a joint'forming region for forming an interlocking joint between an encircling seal and overlapping ends of a strap encircled into a strap loop about an object, strap gathering means for supporting; the overlapping strap ends during joint formation, and seal feed means for feeding a seal into the joint forming region prior to formation of ajoint, a

latch bolt latched to hold the strap gathering means, retracted out of strap supporting position, said seal feed means a igned to actuate the latch bolt and unlatch it during the seal feed stroke ,to allow the strap gathering means to extend to a position supporting the overlapping strap ends, means to actuate the joint forming means on a forward stroke to cause a joint to be formed between the seal fed in and the overlapping strap ends and to thereafter return the joint forming means to its original position on a return stroke, said return of the joint forming means causing relatching and return of the latch bolt and return of the strap gathering means out of strap supporting position.

8. The combination defined by claim 7 characterized by said latch bolt being in the form of a plunger both connected to a first latch plate driven by said joint forming means and spring biased toward its latched position into engagement with a second latch plate, said second latch plate being connected to actuate the strap gathering means, actuation of the latch bolt by actuation of the seal feed means during the seal feed stroke causing the latch bolt to be unlatched and disengaged from the second latch plate to allow the second latch plate to move the strap gathering means toward strap supporting position, actuation of the joint forming means during the. forward joint forming stroke causing movement of the first latch plate to cause the latch bolt to reengage the second latch plate, whereby upon the return stroke of the joint forming means the first latch plate through its engagement with the latch bolt causes return of the second latch plate which in turn causes the return of the strap gathering means out of strap supporting position.

9. The combination in a strapping machine comprising, seal feed means for feeding a seal to a position about two overlapping strap ends, joint forming means for forming an interlocking joint between the seal and the overlapping strap ends, and strap gathering means for supporting the overlapping strap ends during joint formation, a latch bolt being provided to hold the strap gathering means retracted out of strap supporting position when the latch bolt is latched to the joint forming means, the latch being in the path of the seal feed means so that the seal feed means unlatches the latch bolt from the joint forming means and allows the strap gathering means to extend to strap supporting position during the seal feed movement of the seal feed means, means for actuating the joint forming means to form an interlocking joint between a seal and the overlapping strap ends and to thereafter cause return movement of the joint forming means, the latch bolt and the joint forming means being so related that the latch bolt is caused to again latch onto the joint forming means during the joint forming stroke and thereafter cause return of the strap gathering means out of strap supporting position upon return of the joint forming means.

10. The combination defined by claim 9 characterized by, said joint forming means also having means coacting with the seal feed means to cause the seal feed means to retract during the joint forming movement.

11. The combination in a strapping machine comprising, means for guiding a length of strap leading from a strap supply and looped around an object, tensioning means for drawing the strap taut around the object, a blade over which said strap passes, jaws for gripping the free end of the strap against the blade, said blade having a portion with transverse grooves formed therein and said jaws having sharp projections to force the material of the strap into the grooves to hold the strap taut during the operation of the tensioning means, joint forming means for joining together the ends of the strap looped and tensioned about the object, and a movable strap shear means for coacting against another portion of the blade for severing the length of strap looped and tensioned about the object from the strap supply.

12. The combination in a strapping machine comprising, means for guiding a length of strap leading from a strap supply and looped around an object, tensioning means for drawing the strap taut around the object, a blade over which the strap passes, jaws for gripping the free end of the strap against the blade, said blade having a portion with transverse grooves formed therein and said jaws having sharp projections to force the material of the strap into the grooves to hold the strap taut during the operation of the tensioning means, strap straightening means for straightening the strap as the tensioning means draws the strap taut about the object, said blade having a curved portion for the strap straightening means to provide a curved path for the strap to effect its straightening.

13. The combination in a strapping machine comprising, strap feed means for feeding a length of strap to be encircled into a strap loop about an object, joint forming means for forming a joint between a seal and overlapping strap ends of the strap loop, seal feed means for feeding a seal to the joint forming region of the overlapping strap ends, the joint forming means having a crosshead for retracting the seal feed means during the joint forming movement of the joint forming means after the seal feed means has fed a seal to the joint forming region, a switch means for controlling said strap feed means, and a connecting link between the crosshead and the seal feed means adapted to actuate the switch means in one direction to render the strap feed means inoperative as the seal feed means is actuated to feed a seal and in its opposite direction upon return movement of the crosshead with the joint forming means to thereby insure inoperation of the strap feed means during the joint forming period.

14. The combination defined by claim 13 characterized by, said connecting link being resiliently flexible to compensate by bending for any changes in distances occurring between the locations on the crosshead and the seal feed means where the connected link is connected during movement of the crosshead, the connecting link and the seal feed means.

15. The combination in a strapping machine comprising, strap feed means for feeding a length of strap to be encircled into a strap loop about an object, a two position switch means for controlling the operation of said strap feed means, joint forming means for forming a joint between a seal and overlapping strap ends of the loop, seal feed means for feeding a seal to the joint forming region of the overlapping strap ends, the joint forming means having a crosshead operably connected to it, a con necting link mounted between the crosshead and the seal feed means and positioned to hold the switch means in one position when both the joint forming means and the seal feed means are retracted, said one position of said switch means rendering the strap feed means operative, the switch means being disengaged from said link and moved to its second position upon movement of the seal feed means during its seal feed stroke to render the strap feed means inoperative, power means for extending the joint forming means to cause a joint to be formed between the seal and overlapping strap ends and cause said crosshead to be actuated in one direction, said crosshead engaging said seal feed means at this time to cause its retraction reversely of its seal feed stroke, said joint forming means being thereafter returnable to its initial position to transport the crosshead to its initial position and thereby cause said link to return saidl switch to its original position which again renders the strap feed means operative.

16. The combination in a strapping machine comprising, tensioning means for tensioning a loop of strap encircled about an object by withdrawing the supply end of the strap relative to its leading end, strap gripping means for holding the leading end of strap stationary during tensioning, an air motor being used to power the tensioning means and an air operated piston used to cause actuation of the strap gripping means, both the air motor and the piston being simultaneously supplied with pressurized air from the same source to cause simultaneous gripping of the strap gripping means and initiation of the tensioning by the tensioning means.

References Cited in the file of this patent UNITED STATES PATENTS 1,650,843 McChesney Nov. 29, 1927 2,215,121 Harvey et a1. Sept. 17, 1940 2,707,429 Leslie May 3, 1955 2,882,814 Winkler et a1. Apr. 21, 1959 2,915,003 Crosby et al. Dec. 1, 1959 

1. THE COMBINATION IN A STRAPPING MACHINE COMPRISING, GRIPPING MEANS FOR GRIPPING THE LEADING END OF A LENGTH OF STRAP ENCIRCLED INTO A STRAP LOOP ABOUT AN OBJECT TO BE STRAPPED WITH THE LEADING END OF THE STRAP OVERLAPPING ITS SUPPLY END, TENSIONING MEANS FOR WITHDRAWING THE SUPPLY END OF THE STRAP LOOP RELATIVE TO THE LEADING END OF THE STRAP LOOP WHILE THE GRIPPING MEANS HOLDS THE LEADING END STATIONARY IN ORDER TO SHRINK AND TENSION THE STRAP LOOP ONTO THE OBJECT, JOINT FORMING MEANS FOR FORMING A JOINT BETWEEN THE OVERLAPPING PORTIONS OF THE STRAP, SAID TENSIONING MEANS HAVING A ROTARY FEED WHEEL AND AN IDLER WHEEL BETWEEN WHICH THE STRAP PASSES WHILE BEING TENSIONED, SAID ROTARY FEED WHEEL SUPPORTED ON A SHAFT DRIVEN BY A POWER MEANS FOR TENSIONING, SAID IDLER WHEEL BEING MOUNTED ON AN ECCENTRIC SHAFT WHICH IS SO ALIGNED RELATIVE TO THE ROTARY FEED WHEEL THAT TENSION IN THE STRAP URGES ROTATION OF THE ECCENTRIC SHAFT AND THEREBY URGES THE IDLER WHEEL BODILY TOWARD THE ROTARY FEED WHEEL TO INCREASE THE GRIP ON THE STRAP PASSED THEREBETWEEN AS STRAP TENSION INCREASES, CONTROL MEANS FOR CONTROLLING THE OPERATION OF SAID JOINT FORMING MEANS, SAID CONTROL MEANS HAVING A PORTION INTERCONNECTED TO SAID ECCENTRIC SHAFT PROVIDING MOVEMENT OF SAID PORTION IN RESPONSE TO SAID ROTATION OF THE ECCENTRIC SHAFT AS TENSION IN THE STRAP INCREASES, THE MOVEMENT OF SAID PORTION BEING SUFFICIENT TO OPERATE THE CONTROL MEANS AND CAUSE OPERATION OF THE JOINT FORMING MEANS. 